Diaphragm for sound-producing instruments



S. B. WILUAMSON. DIAPHRAGM 'FOR SOUND PRODUCING INSTRUMENTS.

APPLCATION FILED OCT.20, 1920.

Patented June 6, 1922.

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UNITED STATES SAMUEL B. WILLIAMSON, OF WESTPORT, CONNECTICUT.

DIAPHRAGM FOR SOUND-PRODUCING ;[NSTRUMEiN'TS.

Speciflcation of Letters Patent.

Patented June 6,1922.

Application filed October 20, 1920. Serial No. 418330.

To all whom it may concem:

Be t known that I, SAMUEL B. WILLIAM- soN, a citizen of the UnitedStates of America, and a resident of. Westport, County of Fairfield,State of Connectic'ut, have invented certain new .and usefulImprovements in Diaphragms for Sound-Producing Instruments, of which thefollowing is aspecifi'cation. 4 w

One of the objects of my invention is to provide a diaphragm which isvery delicate and responsive in its nature so as to take up thevibrations of the sound initiatin'g instrumentalities and likewiseequally delicate and accurate in reproducing same.

Another object of my invention is to so form the diaphragm as toeliminate to a gr'eater degree than heretofore attained the nasalqualities of the voice and at the same time to do away with all scratehynoises; and in carrying this phase of my improvement into efect Iprovide a sound screen, or sifter, integral with, and midway of, thediaphragm structure, which will arrest and eliminate these undesiredvibrations and permit the undiluted ori inal 'tones to arrive at, anddepartfrom, the outer, or sound, delivering surface.

I further in my invention and improved diaphragm contenplate and attaina much greater vibratory activity than heretofore achieved in anysimilar instrumentality of like dimension; in fact I secure an amplitudeof vibration equal to that which would ordinarilybe obtained in adiaphragm of four or five times the area; that is under present constructions.

Another, and very important, object secured by me in the engineering ofny preseut improvement s that I provide a structure which will securethe harmonious reproduction of orchestras, so that the orchestra, as awhole, is truly and accurately reproduced and the accentuating of anyspecial instrument is entirely avoided.

Another object of my invention, which I will hereinafter explain atlarge, is the separation' of the sound producing zone of my diaphragmfrom that part of the diaphragm whi 'li is attached to its supports; andin this way and through this arrangement the diaphra gm is permitted tovibrate unhampered and unhlndered by .its supporting agencies:

thegreat difliculty experienced in this re-.

spec-t was, and is, that the diaphragm, in vi bratng, transmtted part ofits activities to 'the box, or container, which latter would thereuponset up a sympathetic and more or less independent action resulting inConflicting sounds: in creating zones, as I will explain, I am enabledto intervene and entirely obviate this drawback. In order to achievethis I will here state, although I will explain it more fully furtheron, that the structure which receives sifts and reproduces the vibrationmust be, as a unit, integral,- that is to say, homogeneous: a built-upor laminated diaphragm always results in individually developedvibrations and consequent interfering and discordant sounds. Thelaminations meddle with one another and instead of amplifying andclarifying the sounds serve only tomuddle and befog: a thiek instead ofa clear sound; a burr instead of abell.

Specifically I provid a cylindrical diaphragm formed of fibrouspaperwith a suiti able binder so blended and disposed as to result in ahomogeneous mass, and `on both faces of the diaphragm I impose asuitable coating` of very fine glue. v

In constructing my diaphragm I provide a relatively large centrallylocated vibrating zone. This zone is as hereintofore indicated, formedof fibrous material with a suitable binder and a coating on each face;it is my desire and purpose to limit the vibrations to this central zoneand not permit them to be communicated to the box or case of thephonograph: to achieve this I provide a concen tric zone immediatelyoutside of and conti guous to the central zone of a conforrnation whichwill operate to halt and cut off the sound vibratious. and I accomplishthis by effecting a compression of the material so that when thevibrations proceeding radially outward from the center of the disc reachthis 'depressed portion 'they will not get across: in other words thisis a dead nonvibrating annular moat which refuses passage to theprogress of the vibrations.

The outer edge or periphery of the dia phragm'may be formed in variousways a: I

will explain, but I cannot too strongly accentuate the necessity andimportance of the annular noat atoresaid. v

This depression or moat also serves to delimit the vibrations andprevents them creeping, and it also in a sense is a sort of hinge forthe outer edge ot' the central zone.

Referring to the accompanyiug drawngs which form part ot' thisspecificatiou,

Figur-e l represents a view partly insection of a phonograph instrument.

Figure 2 indicates the same inplement on the line lI-II Figure l.

Figure 3 is a cross section of my improved diaphragm as it is shapedpreliminarily.

Figure 4 is a similar View of the diaphragn after it has been treatedwith the coating material.

-Figure 5 shows the conformation ot' the diaphragm after it has beensubject to compression: in this View appears the main central vibratingzone, the depressed concentric zone surrounding same which depression isdesigned and intended for shutting of and stopping the outward radialtravel ot' the vibrations of the central zone thereby preventing saidvibrations from reaching the phonograph case or box and setting upindependent and confiicting vibrations; in this view is also shown theouter or pe'ipheral zonepo'sitioned in the complete 'structure to beembraced and held in position by the diaphragm supporting agencies ofthe phono-' graph case. In this figure also I show the centralperforation designed to receive the needle arm.

Figure 6 represents the diaphragm with the immediate 'supportingagencies consisting of the peripheral rings; this view also shows thecentral attachment.

Figures 7 and 8 show modified forms of diaphragms.

At 12 is the peripheral rim which in cross section is full size, thesame size in cross section as the central zone 13. Between the centralzone 13 and the peripheral rim 12 is the annulardepression 14 positionedconcentric with the central zone and formed by pressing in upon thediaphragm from both sides. This annular depression 14 is arranged in theouter portion of the diaphragm and contiguous to the final outer rim 12.The physical efi'ect of this distribution of zones is that when thecentral area becomes agitated by the needle arm the amplitude of theresulting vibrations of the diaphragm will be greatest at the centralpoint, the vibrations tending to decrease as they approach theperipheryz nevertheless at the periphery 'there will be some activitywhich if unsuppressed will be communicated to the parts of thephonograp'h structure which serve as peripheral supports; this latterdefeat, which attaches to all present forms of phonographs, I purposeeliminating by means of the depression 14 for when the radial travel ofthe vibrations, moving from the central point outwards, reach thisdepression they are halted as said depression by reason ot' its positionand inherent rigdity will operate as a stop; the -vibrations in otherwords will not get across the zone 14.

In Fgure T I show a modifiedform of depression; here the annular grooveis on one side of the disc only: in Figure 8 is another form: in thisinstance it is a sort of platform 16. The principle in all of these isthe same however and that is a wave stop between the central vibratingzone and the phonograph box.

At 17 is the central perforaton to accommodate the screw 18 forattaching the needle arm 19.

At 20 are peripheral rings of rubber or other suitable material andthese latter embrace and retain the disc at its outer edge.

At 21 is the needle held in the needle arm 19 by adjusting screw 22 andat 23' is shown the record disc. These latteriare conventional forms andneed not be enlarged upon.

Having thus described my invention the following is what I claim as newand useful therein and desire to secure by Letters Patent.

l. A circular sound producing diaphragn 95 formed throughout of fibrousmaterial with a compressed concentric zone between the center andperiphery.

2. A sound producing diaphragn formed throughout of homogeneou-s fibrousmaterial 100 and comprisinga main central portion and a p concentriccompressed depression positioned between the periphery and the center.

3. A sound producing diaphragm formed throughout of honogeneous fibrousmaterial and comprising a main central portion and a concentriccompressed depression position'ed relatively nearer the periphery thanthe center.

4. A sound producing diaphragn for-med 110.

throughout of fibrous material, and comprising a main centralrin-compressed vibrating zone, and a concentric zone positionedrelatively near theperiphery sufliciently compressed to permitindependent vibrating acllv tivities of the central zone.

5. A sound reproducing diaphragm formed v throughout 'of fibrousmaterial, and comprising a main central uncompressed vibrating zone,'and a concentric compressed de- .pression positioned exterior to thesaid main material, and comprisng a main central iribratmg. zone, wth aconcentrc exteror zone of greater densty than the central zone.

8. The method of making diaphragms for 5 sound pmducing instrumentswhich consists in providin a cylindrcal disa of fibrous paper having ander so blended and disposed as to result in a homogeneous mass,applying on both facesof the diaphragm a coating of very fine glue andfinally b compression forming a zone of diminshe crosssection contiguoustothe periphery of the diaphragm. V

. SAMUEL B. WILLIAMSON.

